Class
ActiveRecord::Schema
<
ActiveRecord::Migration::Current

Active Record Schema

Allows programmers to programmatically define a schema in a portable DSL.
This means you can define tables, indexes, etc. without using SQL directly,
so your applications can more easily support multiple databases.

Eval the given block. All methods available to the current connection
adapter are available within the block, so you can easily use the database
definition DSL to build up your schema ( create_table,
add_index,
etc.).

The info hash is optional, and if given is used to define
metadata about the current schema (currently, only the schema's
version):